DESCRIPTION: (Applicant's Abstract) Prenatal cocaine exposure likely has profound consequences for infants' emotional behavior in response to frustration and/or challenge. This project examines the mediating effect of stress reactivity on the relation between cocaine exposure and emotion expression and regulation. It is our hypothesis that prenatal cocaine exposure results in an altered reactivity to stress which leads to dysfunctional emotional regulation. Two longitudinal studies are proposed. One study of infants at 2, 6, 12, and 18 months of age will assess relations between cocaine exposure, altered stress reactivity, and dysfunctional emotional regulation. Given that prenatal cocaine exposure adversely impacts on stress reactivity, another aim of this project is to determine whether there are exposure group differences in infants' abilities to regulate stress when presented with stress reducing procedures. Normative research with newborn infants has found that the taste of sucrose has a powerful calming effect when compared to other substances such as water (and to different calming agents like pacifiers). The second study will examine the relative calming efficacy of sucrose (as opposed to water or no treatment) on stress regulation in newborns and 12-month-olds as a function of prenatal cocaine exposure. It is our hypothesis that cocaine exposure is associated with a diminished sucrose calming effect at birth. In light of normative evidence for a sucrose calming effect throughout infancy, this study also will test for exposure group differences in sucrose calming efficacy on stress regulation at 12 months of age. In both studies, the effects of both medical and environmental risk will be considered in evaluating the effects of prenatal cocaine exposure.